I walked from Porto to Santiago, then from Fisterra to Muxia in late Apr-May and from Santatem to Porto in late Oct. Re Lisbon-Porto route: the stages before Coimbra are the longest but they are the most beautiful in terms of nature. Albergues are all there apart from Tomar, there is a nice hostel there. The route is not yet busy so I guess there won't be any problems to stay in albergues if you cycle. Make sure you have plenty of water and some snacks with you - there are not many options where you can eat or fill your bottle in. From Coimbra to Porto: busier roads, more populated area, less pleasant to walk, plenty of road walking, and cobblestones to remember but the stages are much shorter. The last one before Porto is a killer though. If I had that option I'd probably cycle between Coimbra and Porto. Porto-Santiago route: much easier in comparison in so many respects. The only slightly challenging stage is a climb after Ponte de Lima. The route between Lisbon and Santiago is not really hilly or challenging so even runners would do there, no need for hiking boots. Would greatly advise to walk between Muxia and Fisterra if you have time after Santiago - the most amazing nature is there. We even decided to stay in between the two, in Lires - that is where I could finally feel the sence of closure and peace within.